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mm: add find_lock_head

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Add a new FGP_HEAD flag which avoids calling find_subpage() and add a
convenience wrapper for it.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Link: https://lkml.kernel.org/r/20200910183318.20139-9-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle)
2020-10-13 16:51:41 -07:00
committed by Linus Torvalds
parent 63ec1973dd
commit a8cf7f272b
2 changed files with 32 additions and 9 deletions
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32
include/linux/pagemap.h
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@@ -279,6 +279,7 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping,
#define FGP_NOFS 0x00000010
#define FGP_NOWAIT 0x00000020
#define FGP_FOR_MMAP 0x00000040
#define FGP_HEAD 0x00000080
struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
int fgp_flags, gfp_t cache_gfp_mask);
@@ -310,18 +311,37 @@ static inline struct page *find_get_page_flags(struct address_space *mapping,
* @mapping: the address_space to search
* @offset: the page index
*
* Looks up the page cache slot at @mapping & @offset. If there is a
* Looks up the page cache entry at @mapping & @offset. If there is a
* page cache page, it is returned locked and with an increased
* refcount.
*
* Otherwise, %NULL is returned.
*
* find_lock_page() may sleep.
* Context: May sleep.
* Return: A struct page or %NULL if there is no page in the cache for this
* index.
*/
static inline struct page *find_lock_page(struct address_space *mapping,
pgoff_t offset)
pgoff_t index)
{
return pagecache_get_page(mapping, offset, FGP_LOCK, 0);
return pagecache_get_page(mapping, index, FGP_LOCK, 0);
}
/**
* find_lock_head - Locate, pin and lock a pagecache page.
* @mapping: The address_space to search.
* @offset: The page index.
*
* Looks up the page cache entry at @mapping & @offset. If there is a
* page cache page, its head page is returned locked and with an increased
* refcount.
*
* Context: May sleep.
* Return: A struct page which is !PageTail, or %NULL if there is no page
* in the cache for this index.
*/
static inline struct page *find_lock_head(struct address_space *mapping,
pgoff_t index)
{
return pagecache_get_page(mapping, index, FGP_LOCK | FGP_HEAD, 0);
}
/**